The signing of Smith, 33, could signify concern that Channing Crowder, who is second on the team with 105 tackles, might not be available because of an injury to his left knee. In his first start of the season, back-up Reggie Torbor, Crowder’s replacement, had one tackle.

With Jets Pro Bowl running back Thomas Jones up next, the Dolphins need to shore up a run defense that has allowed more than 110 rushing yards in four of the past five games.

Smith, a third-round pick in 1997 by the Redskins out of Arizona State, played four seasons with the Redskins and seven with the 49ers before landing with the Chargers last spring. He played five games and started the first four for the San Diego, totaling 35 tackles. But the Chargers released him on Nov. 12.